Operative monitoring of stress-strained state of the containment shell during NPP construction

The results are outlined of full-scale observations and stress analysis of the containment shell of the Novovoronezhskaya NPP after pressurization and testing. The results are compared with the projected and rated data. The containment shell under consideration is a hollow reinforced concrete cylinder locked at the top with a smooth semispherical dome. The cylinder rests upon a foundation. It is shown that the strains measured in unstressed reinforcement in all points have proven to be below the rated tensile strength of the reinforcement (340 MPa). The maximum tensile strains have been measured in the zone of the dome conjugation with the supporting ring. Compression strains in concrete have not exceeded their rated strength (14.9 MPa). The maximum compression strains in concrete (10.6 MPa) have been measured in the middle part of the cylinder in the radial direction. The strains measured in the metal cladding have proven to be considerably lower than the rated values. A conclusion is drawn that it is necessary to equip the NPP containment shells with instrumentation for rapid monitoring of the shell strains and deformations when testing the shells for pressurization and excessive pressure